From: David Miller <davem@davemloft.net>
To: jslaby@suse.cz
Cc: alexei.starovoitov@gmail.com, mingo@kernel.org, mingo@redhat.com,
tglx@linutronix.de, hpa@zytor.com, x86@kernel.org,
jpoimboe@redhat.com, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, daniel@iogearbox.net,
edumazet@google.com
Subject: Re: [PATCH v3 07/29] x86: bpf_jit, use ENTRY+ENDPROC
Date: Mon, 24 Apr 2017 14:24:20 -0400 (EDT) [thread overview]
Message-ID: <20170424.142420.290668473718207530.davem@davemloft.net> (raw)
In-Reply-To: <26f5afd7-d70b-effa-e528-8d0a2b95717a@suse.cz>
From: Jiri Slaby <jslaby@suse.cz>
Date: Mon, 24 Apr 2017 19:51:54 +0200
> For example what's the point of making the sk_load_word_positive_offset
> label a global, callable function? Note that this is exactly the reason
> why this particular two hunks look weird to you even though the
> annotations only mechanically paraphrase what is in the current code.
So that it can be referenced by the eBPF JIT, because these are
helpers for eBPF JIT generated code. Every architecture implementing
an eBPF JIT has this "mess".
You can't even put a tracepoint or kprobe on these things and expect
to see "arguments" or "return PC" values in the usual spots. This
code has special calling conventions and register usage as Alexei
explained.
I would suggest that you read and understand how this assembler is
designed, how it is called from the generated JIT code, and what it's
semantics and register usage are, before trying to annotating it.
Thank you.
next prev parent reply other threads:[~2017-04-24 18:24 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-21 14:12 [PATCH v3 01/29] x86: boot/copy, remove unused functions Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 02/29] x86_32: boot, extract efi_pe_entry from startup_32 Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 03/29] x86_64: boot, extract efi_pe_entry from startup_64 Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 04/29] x86: assembly, use ENDPROC for functions Jiri Slaby
2017-04-26 1:42 ` Josh Poimboeuf
2017-05-12 7:53 ` Jiri Slaby
2017-05-12 22:15 ` Josh Poimboeuf
2017-05-17 13:23 ` Jiri Slaby
2017-05-19 9:17 ` Jiri Slaby
2017-05-19 19:50 ` Josh Poimboeuf
2017-04-21 14:12 ` [PATCH v3 05/29] x86: assembly, add ENDPROC to functions Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 06/29] x86: assembly, annotate functions by ENTRY, not GLOBAL Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 07/29] x86: bpf_jit, use ENTRY+ENDPROC Jiri Slaby
2017-04-21 19:32 ` Alexei Starovoitov
2017-04-24 6:45 ` Jiri Slaby
2017-04-24 14:41 ` David Miller
2017-04-24 14:52 ` Jiri Slaby
2017-04-24 15:08 ` David Miller
2017-04-24 15:41 ` Jiri Slaby
2017-04-24 15:51 ` David Miller
2017-04-24 15:53 ` Jiri Slaby
2017-04-24 15:55 ` Ingo Molnar
2017-04-24 16:02 ` Jiri Slaby
2017-04-24 16:40 ` Ingo Molnar
2017-04-24 16:47 ` Alexei Starovoitov
2017-04-24 17:51 ` Jiri Slaby
2017-04-24 18:24 ` David Miller [this message]
2017-04-25 14:41 ` Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 08/29] linkage: new macros for assembler symbols Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 09/29] x86: assembly, use DATA_SIMPLE for data Jiri Slaby
2017-04-27 11:53 ` Pavel Machek
2017-04-27 12:30 ` Jiri Slaby
2017-04-27 12:43 ` Pavel Machek
2017-04-21 14:12 ` [PATCH v3 10/29] x86: assembly, annotate relocate_kernel Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 11/29] x86: entry, annotate THUNKs Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 12/29] x86: assembly, annotate local functions Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 13/29] x86: crypto, " Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 14/29] x86: boot, " Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 15/29] x86: assembly, annotate aliases Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 16/29] x86: entry, annotate interrupt symbols properly Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 17/29] x86: head, annotate data appropriatelly Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 18/29] x86: boot, " Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 19/29] x86: um, " Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 20/29] x86: xen-pvh, " Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 21/29] x86: purgatory, start using annotations Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 22/29] x86: assembly, use SYM_FUNC_INNER_LABEL instead of GLOBAL Jiri Slaby
2017-04-21 14:12 ` [PATCH v3 23/29] x86: realmode, use SYM_DATA_* " Jiri Slaby
2017-04-21 14:13 ` [PATCH v3 24/29] x86: assembly, remove GLOBAL macro Jiri Slaby
2017-04-21 14:13 ` [PATCH v3 25/29] x86: assembly, make some functions local Jiri Slaby
2017-04-21 14:13 ` [PATCH v3 26/29] x86_64: assembly, change all ENTRY to SYM_FUNC_START Jiri Slaby
2017-04-21 14:13 ` [PATCH v3 27/29] x86_32: " Jiri Slaby
2017-04-21 14:13 ` [PATCH v3 28/29] x86_32: lguest, use SYM_ENTRY Jiri Slaby
2017-04-21 14:13 ` [PATCH v3 29/29] x86: assembly, replace WEAK uses Jiri Slaby
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